The statements in this section merely provide background information related to the present disclosure and may or may not constitute prior art.
Coil compression springs find wide application as energy storage devices in power train components where they temporarily absorb driveline transients and smooth power delivery. They are frequent and common components of manual transmission clutches, disposed between drive and driven components where they lessen driveline shock and smooth clutch engagement.
In such applications, the coil spring is frequently installed not in a straight line, helical configuration but in an arc, its radius of curvature dictated by its distance from the center axis (of rotation) of the clutch. The installation of a coil compression spring in an arc creates a plethora of engineering, design and service issues.
For example, whereas the bottoming of a conventional straight helical coil spring occurs essentially everywhere along a helical line of contact between adjacent coils, bottoming of an arc coil spring occurs only proximate its inner diameter in the region where the coils are closer in its uncompressed state. In fact, only a very small region of each coil may carry the bottoming load. Thus, coils of an arc coil spring are subjected to higher stress for the same bottoming load relative to a straight helical spring since only a portion of each coil carries the load.
Another engineering issue relates to the outer surface of an arc coil spring. Almost without exception, an arc coil spring is constrained within a guide or housing which maintains the spring in its proper position between end points. Specifically, it is the outer surface of the arc coil spring that must be constrained and this is generally accomplished by a curved housing that at least partially surrounds the arc spring. Accordingly, there will typically be significant force and friction between the outer surface of the arc spring and the inner surface of the curved spring housing.
The present invention is directed to solving these problems and improving the performance and service life of arc coil springs.